Low temperature hydraulic medium



masses before solidification.

it i are; July 20, 1943 Nlf'lEDf STATE assure inwrnmnna'runs nrnmiuuc mum Theodore R. Donlan, Union, N. 1., assigimr to Standard Oil Development Company, a cor poratlon of Delaware No Drawing.

Application January 2, 1941, g Serial no. erases 3 Claims. (01. 252-76) .This invention relates to liquid compositions suitable'for use influid cooling and in fluid pressure transmitting. systems. -It relates particularly to anti-freeze compositions for the cooling systems of automobile engines.-

It is well recognized that water is the most advantageous lfluid cooling and fluid pressure transmitting medium at temperatures above its freezing point. The disadvantages, however, 'of

'its use at temperatures below its freem'ng point are such as to preclude it's use in cooling systems and pressure transmitting devices which are likely to be operated at such low temperatures. Some improvement has been effected by dissolving in water substances which effect a lowering of the freezing point and which also effect a reduction of the relative degree of expansion upon solidiilcation. Thesubstances-employed in these capacities are ofv two .types, namely electrolytes,

suchjas calcium chloride: and organic compounds miscible with water, of low; freezing points and viscous "consistencies at low temperatures such as the alcohols. 0f these two types, the organic compounds are generally considered preferable,

. because of the less corrosive nature of their aqueous, solutions and the formation of viscous The compositions of the invention have, in ad ,compounds of invention employed a inhibitors for fluid cooling fluid pressure transmitting. devices are effective in repressing the corrosion of all'types of metallic surfaces likely to he encountered in the'fabrication of automo- -bile radiators) and they are also without effect on rubber.

An'object of this invention is the preparation of compositions suitable for use in'the cooling systems of automobile engines and other internal combustion engines, which are substantially noncorrosive to various metals in contact with one another in the automobile cooling system even when diluted with water in large quantities, and which do not readily deteriorate under service conditions or cause the deposition of gummy or resinous materials which impede the functioning of the cooling liquid.

Otherobje'cts of the invenfion will be apparent from the reading of the following description.

dition to the usual constituents of hydraulic media suitable for use at low temperatures, small amounts of the phthalates of the metals above aluminum'in the electromotlve series of the ele- -ments. Among the phthalates which are particularly advantageous are those of the metals It has been found necessary to combat even i this mild form of corrosion of the organic solutions when employed in the. cooling system of internal combustion engines. The automobile cooling system consists essentially of three parts, the metal framework, the liquid heat transfer medium, and the mechanism for circuiatihg the liquid in the metal framework. In the operation of theengine local'overheatin'g occurs, andidue .ofsfidium, potassium, barium, calcium and magnesium. It has been found that small quantities to the many and varied metal contactsfin-the metal framework and to air which may pass through the system as a result of the leakage o! air through the pumping and packing equipment, corrosion occurs in many-partsas a result of oxidation and development of electrochemicalreof these phthalates in the compositions are particuiarly eilective as corrosion inhibitors for repressing the deterioration of the metallic surfaces and particularly the solder Joints in the metal framework, Furthermore there is reason to believe that the phthalates contribute appreciably to the formation ofan antf-corrosivefllm over the surface of the metals of the 'iramework of the radiator system.

Thus compositions within the scope of themvention usually'contain a monohydrlc aliphatic alcohol containing up toabout six carbon atoms.

lotions at the metallic surfaces. To repress this ..co'rrosion the compounds employed as'inhibitors must be sensitive :to the reactions involved especially as those with solder in view of its use as a lower glycol, glycerol or a mixture thereof; water; the phthalate compound; an anti-leak agent such as linseed when a glycol is employed;

, sometimes an anti-foaming agent especially when a glycol is employed: and sometimes a dye maa jointing material. Furthermore, the solutions must be. without effect upon rubber which is usually employed as a flexible connection be:

tween c rtain partsof the radiator system. The 50 terial. In preparing compositions according to the invention a concentrated composition is first prepared andthen by-diiutlng the concentrate with water in various amounts the hydraulic i the following composition:

media 01 various freezing points'are prepared.- The amount of the phthalate added as-a corros ion inhibitor varies between about 0.1% and 2.0% of the weight oi. the composition that is prepared as a concentrate.

An example illustrative of the invention has Per cent of methyl and isopropyl alcohols (specific gravity 0.809) 99 Water To. which is added a Gms.-/gal. Phthalate corrosion inhibitor 4 sodium nitrite a National Alphamrrine-sG-dye'. 0.04

This composition is illustrative of a-concentrate which is capable of dilution with water in any degree and thus permits the preparation oi hydraulic media for a wide range of low temp rature characteristics. Thusfor protection to temperatures of about20' It. a 15% aqueous solution is prepared and for temperatures of about- 0 1''. a 30% aqueous solution is prepared.

*Il'i'the pre 11 or concentrates according assume poundis' generally oi its low cost and its solubility in the alcohols. v

The phthalate compounds employed in this invention have been found to give an added efiect. Thus, the alkali metal nitrites have been employed in the prior art as anti-corrosive agents, but their use in anti-freeze solutions as corrosion inhibitors is disadvantageous because of their activity on solder in contact 'with copper. The phthalate compounds oi this invention have the particularly desirable feature oi repressing the' corrosive activity 01. the alkali metal nitrites upon solder in contact with copper, .while maintaining the elect or these nitrltes 111 111:-

hibiting the corrosion of iron. A composition eontaining both a phthalate and nitrite compound isexemplified in the specific concentrate shown as an-embodiment ot the ,invention.

The nitrite of any of the alkali'metals may be employed instead of, sodium nitrite,as indicated in the specific example. These nitrates are added to the concentrates in. amounts .between 0.5 and 10' grams per gallon but usually the amount is between 1.5 and 6 grams per gallon.

to the above type, mixtures of methyl and isopropyl alcohols may vary inranges tram-90 to 10% oi methyl alcohol and from 101:0 90% -ot isopropyl aloifliol. Instead of such alcohols.

ethyl alcohol or any oi the other lower aliphatic monohydrlc, or dihydric alcohols or glycerol may be used. The alcohols which are suitable in this invention are the m c and polyhydric aliphatic alcohols containing up to six carbon, atomsinthemolccule,andoi'thesethepreierred -alcoholsarethoucontainingonetoiourcarb0n atoms .in the molecule. and particularly methyl,

ethyl, propyl and isop'rop'yl alcohols, ethylene glycol and 1-2 propylene glycol and glycerol. Ad;

-.vantagesotusingtheslycolsandglycerolsare that in addition to their low ireeslng and high boiling points they become highly viscous at low temperatures beiore solidliylng, and that except for the very dilute aqueous solutions ex-' pansion at lowtemper'atures does not crack the radiator or englnwblock oirthe automobile.

A disadvantage oi certain oi tion oi. anti-freue solutions is that of ing tothe composition a-capaeity to leak creep through minute solder poresandcrevlces.

. To counteract such losses of compounds of the type oi linseed meal are incorporated in the compositions. Other compounds which may be' used to reduce-leakage are gum gambler. traga- 'canth, quince'aeed. Irish moss and their mixtures. otherwelldisp'ersedsolidsmaybeincluded. such as paper palm-aluminum or hrc'ise, but in general linseed or fiaaseed meal are preferred 'bec'auseoithesuperiorreaultsobtainedand their clean appearance. The amounts in which these materials-are incorporatedin the anti freeze composition usually about 5 grams per gallon oi concentrateamount -oi water in the concentrated composi is roughly that givenin the specifics:-

ample, although less concentrated alcohols conmulsinthepi'epara- I 4. Compositionh in (-1,-)'.

The dye material is added in small amounts to the composition in order to impart distinctive and attractive appearance ji'or sales purposes. Any suitable dye material can be used instead of National Alph'izurine-ZG' as given in the specific composition which is presented as an illustration oi the invention. I The order and method oi mixing the'various ingredients may be varied to suit the equipment I-Vtflll'l'e 101' blending. The blenrhng-e'quipment "may be any suitable form of homogenizing means as-a colloid mill or equivalent device for producing violent agitation capable oi eiiccting fine Sodium nitrite. a Elm/Idlof mi.

, above. together with Sodimn-phthalate; 4 gun/gal. oi alcohol mp sition as in (1) above, together .with

Sodium nitrite, 8 gun/gal. oi'alcohol concentrate Sodium 'phthalate, 4 gull/gal. ialcohol 'Ihese compositionshad i'reesing points 10' r. it is correct tostatethat these compo- -taining larger amounts of water may also be used.

phthalates of the metals abov'e aluminumin the' specific example. These nitrites are added to the concentrated compositions in amounts between 0.5 and 8 grams per gallon and preferably in an amount between 2 and 5 grams 1 in-the test-solution to half their length in a suitsitionshad freezing mlntsoi-aboutlll r. be-

cause at aboutthat temperature super cooling and latent heat effects occur andthrmshoutlhe mass the formation of malice .is'noticeable.

- Theabove'compositions were testqi for corrosion by means of the following procedure:

Strips of various metals h'r'f x 3' 1 %")-were fastened to a stainless steel support and immersed able flask vented-toithe air by a long glass tube air condenser.- The fiask was placetlin a eonstant temperature hathmaintained at 71 C. :3;

7 per gallon. 01 these eom- 75 5 C. for 144 hours. 'The strips werecaremlly Weight differentials of strips Solution No. Al unn- Copper Hum Brass Solder 0.5 -l.8 0.3 -l.7 +1. 9. 9 +0. 8 +0. 6 +0.3 8.6 -0.6 -ll.8 +0. 4 +1. 5 +0.6 +0. 1 +0. 1 8. 0 0. 0 +0. 8

These data indicate that the composition con- .aining sodium phthalate has very low corrosive effects, especially upon solder and that the combination of sodium phthalate and sodium nitrite is particularly eifective in suppressing corrosive tendencies of aqueous alcoholic solutions. Furthermore, it is reasonable to presume the rates of corrosion of the various metals under the conditions of the test are many times greater than those which would occur in the use of such liquids as cooling media in the automobile engine system. The above solutions containing sodium phthalate when tested in an automobile radiator did not develop foam or evaporate to an objectionable extent.

The description of the invention which has been given is illustrative. It is to be understood that while specific examples have been given for purposes of illustration, the invention is not to be limited thereby. It is to be understood that the phthalate compounds disclosed in the description for incorporation in aqueous hydraulic media may be used either singly or in combination and that these phthalate compounds are as applicable to individual aliphatic alcohols of the range given as to mixtures thereof. Other means of applying the principle of the invention may be employed without departing from the scope of the invention so long as the ingredients stated by any of the following claims or the equivalent of such stated ingredients be employed.

What is claimed is:

1. A liquid composition suitable for use in heat exchange and pressure transmitting devices comprising a mixture of an aliphatic alcohol containing up to 6 carbon atoms in the molecule and water as the main ingredients and a quantity of a phthalate of a metal above aluminum in the electromotive series in corrosion-inhibiting proportions, which phthalate has no substituted components on the benzene ring.

2. A liquid composition according to claim 1 in which the phthalate is an alkali metal phthalate.

3. A non-corrosive liquid composition suitable for use in the cooling systems of automobile engines which comprises a mixture of methyl and isopropyl alcohols and water as major ingredients and an alkali metal phthalate and sodium nitrite as minor constituents in corrosion-inhibiting proportions, the phthalate having no substituted components on the benzene ring.

THEODORE R. DONLAN. 

